loss of power

yo I have a 90 b2600i and I have loss of power the truck starts backfireing, ans a smell os unspent fuel at the tail pipe when it has reached operateing temp. dose anybody have any ideas on what it could be,
I already changes=
-o2 sensor
-plugs
-cap&roater
-wires
-maf from a j-yard
-referb ecu due to other problems.

thanks 90_666

hmm and it is injected, well only thing i can think of maybe is a seal on an injector, if its not sealed properly youll lose fuel pressure and in turn loss of power, also will make your timing seem off because of the backfire. the unspent gas may not be at the pip but at the motor and your just smelling the fumes, of not you might have a dead cylinder where fuel is being dumped into and shooting it back out

Yah check the o-rings on the injectors. Mine did something like that when one of the o-rings was gone.

rip that catylitic converter riiiight out

lol you and no cat haha

TIMING!!!!!!!!!!!!! retime that sucka... i had a similar issue, and just retimed it, and it all cleared right up

Question: How can u lose something u never had?Lol.BJ